Establishment And Analysis Of Piglet Model Of Autism

Autism spectrum disorder（ASD,described as autism in brief hereafter）is a heterogeneous neurodevelopment disorder caused by genetic and environmental factors,with changes in brain development and gene expression.Valproic acid（VPA）is a commonly used antiepileptic drug,however,human epidemiological studies have found that exposure to VPA medication during pregnancy is an important risk factor for autism in offspring.Prenatal treatment with VPA had been applied to develop autism animal models in both rodents and in non-human primates,further confirming the epidemiological finding of a causal effect of prenatal VPA exposure on the autism risk and providing animal models for autism research.As a new model animal,piglets can be anatomically,biochemically,and physiologically closer to humans than rodents,and have fewer ethical constraints on research and more reproductive convenience.Here,for the first time,we explored to use maternal VPA-induced offspring piglets as an animal model of autism,and examined changes in behavior,brain tissue structure,neuron morphology and gene expression of these model piglets.According to different critical periods of embryonic development,three batches of offspring piglet animal models were generated by intraperitoneal injection of different dosages of VPA to the mothers in the first and second trimesters of pregnancy.All pups from the mother injected with 200mg/kg VPA in the second trimester died after birth,with severe body malformation.Offspring piglets generated by mothers with injection of 50 mg/kg VPA in the second trimester or with 75mg/kg VPA in the first trimester,could survive but exhibited gait deficits,abnormal social behavior,increased anxiety and reduced learning and memory ability.The 75 mg/kg VPA-induced piglets had abnormal cerebral cortex structure,with the surface area of their motor cortex（M1）significantly reduced and the sulci and gyri pattern of their temporal cortex significantly altered compared to normal piglets.Golgi of the medial prefrontal cortex（m PFC）of piglets showed that the total length of the basal and apical dendrites of layer V/VI pyramidal neurons and the complexity of dendritic branches were significantly reduced;whereas the density of dendritic spines of these neurons was significantly increased.This is consistent with autism-like behavioral phenotype of these piglets.Transcriptome sequencing analysis showed that maternal exposure to VPA led to abnormal expression of genes of the dopaminergic receptor-related pathways in the m PFC of offspring piglets,suggesting that abnormal brain dopaminergic synaptic transmission is involved in the pathological process of autism-like behavior.In conclusion,we successfully constructed a pig model of autism,further demonstrated the link between maternal VPA exposure and neurodevelopment abnormalities and autism susceptibility and laid a foundation for further research on the neural and pathological mechanisms of autism.